Star Trek: Orion's Hounds (Titan #3)

As the U. S. S. Titan ventures beyond the outermost reaches of known space, the telepaths in her crew—including Diplomatic Officer Donna Troi—are overwhelmed by an alien cry of distress, leading the ship to the scene of a shocking act of carnage: a civilazation of insterstellar “whalers” preying upon and exploiting a familiar species of sentient spacebource giants.

Appalled but reluctant to rush to judgement, Captain William Riker and his crew in investigate, discovering a cosmic spawning ground in a region of active star formation—the exosystem for a bewildering array of diverse but similarly vast life-forms. While attempting to negotiate an end to the victimizeation of these creatures, Riker’s crew inadvertently grants them the means to defeat their hunters’ purpose…only to learn that things are not exactly as they seem.